The deposition of a benefit agent onto a substrate, such as a fabric, is well known in the art. In laundry applications typical “benefit agents” include fabric softeners and conditioners, soil release polymers, sunscreens; and the like. Deposition of a benefit agent is used, for example, in fabric treatment processes such as fabric softening to impart desirable properties to the fabric substrate.
Conventionally, the deposition of the benefit agent has had to rely upon the attractive forces between the oppositely charged substrate and the benefit agent. Typically this requires the addition of benefit agents during the rinsing step of a treatment process so as to avoid adverse effects from other charged chemical species present in the treatment compositions. For example, cationic fabric conditioners are incompatible with anionic surfactants in laundry washing compositions.
Such adverse charge considerations can place severe limitations upon the inclusion of benefit agents in compositions where an active component thereof is of an opposite charge to that of the benefit agent. For example, cotton is negatively charged and thus requires a positively charged benefit agent in order for the benefit agent to be substantive to the cotton, i.e. to have an affinity for the cotton so as to absorb onto it. Often the substantivity of the benefit agent is reduced and/or the deposition rate of the material is reduced because of the presence of incompatible charged species in the compositions. However, in recent times, it has been proposed to deliver a benefit agent in a form whereby it is substituted onto another chemical moiety which increases its affinity for the substrate in question.
WO 99/36469 is directed to a polysaccharide conjugate capable of binding cellulose. Locust bean gum (LBG) is grafted to proteins, such as enzymes or anti-bodies or perfume loaded particles. This is delivered to the fabric during the laundering. The LBG attachment is achieved by enzymatic oxidation of the LBG using galactose oxidase to introduce aldehyde groups. These aldehyde groups are then reacted with glucose oxidase (using sodium cyanoborohydride) to form an LBG with chemically bound glucose oxidase. This procedure for preparing the material is cumbersome and involves numerous steps using ‘conventional’ organic (enzymatic) chemistry, such as purification of LBG, introducing aldehyde functionality to the LBG and coupling of this to an enzyme (via the enzymes hydroxyl functionality).
WO 99/36470 is also directed to polysaccharide conjugates that are able to bind cellulose, where the polysaccharide is attached to a particle containing perfume. The particle may be a range of materials, including silica. Perfume is allowed to infuse into macroporous silica particles simply by absorption, adsorption, impregnation and encapsulation. The polysaccharide, e.g. LBG, is then merely added to the perfumed particles and is physically adsorbed onto the particle surface. The LBG aids deposition in a wash environment. Alternatively, chemical attachment may occur by enzymatic oxidation of polysaccharide side chains
European patent application number 01306632.9 is directed to a water dispersible particle comprising a deposition enhancing part of one or more polymeric units and a benefit agent attached to the deposition enhancing part characterised in a particle size of 20 to 5,000 nm. Preferably the deposition aid must have a hydrolysable group (based on esters), such as Cellulose Mono-Acetate (CMA). The modified particles are prepared by reaction of acid functional beads by a cumbersome multi-step ‘conventional’ organic chemistry technique. This requires several time consuming (and commercially nonviable for high volume production) centrifugation stages and the preparation of an amine functional CMA by reaction of CMA with ethylene diamine using carbonyl diimidazole as coupling agent. The amine functional CMA is then reacted with acid functional beads (obtained externally) using ethyl dimethyl aminopropyl carbodimide as coupler. This results in CMA grafted particles which exhibit enhanced wash deposition.
WO-A-00/18861 provides a water-soluble or water-dispersible material for deposition onto a substrate during a treatment process, wherein the material comprises:                (i) a deposition enhancing part having a polymeric backbone; and        (ii) a benefit agent group attached to the deposition enhancing part by a hydrolytically stable bond;such that the material undergoes during the treatment process, a chemical change which does not involve the hydrolytically stable bond and by which change the affinity of the material onto the substrate is increased. The preferred materials are substituted polysaccharides.        
Thus, all the prior art is directed to the use of ‘conventional’ organic synthesis techniques to add the polysaccharide to the benefit agent. Such routes are cumbersome and many require numerous centrifugation stages to isolate and purify the final modified material. Such routes would not be commercially viable for the production of large volumes of materials.
Emulsion polymerisation techniques are described in “Emulsion Polymerisation and Emulsion Polymers”, P. A. Lovell and M. S. El-Aasser (eds.), John Wiley and Son Ltd (1997). Core/shell emulsion polymerisation techniques are described in L. W. Morgan, J. Appl. Polym. Sci., 27, 2033 (1982), V. L. Dimonie, A. Klein, M. S. El-Aasser and J. W. Vanderhoff, J. Polym. Sci., Polym. Chem., 22, 2197 (1984), D. I. Lee, in “Emulsion Polymers and Emulsion Polymerisation” D. R. Bassett and A. E. Hamielec (eds.), ACS Symposium Ser., No. 165, p. 405 (1981) and W. D. Hergeth, K. Schmutzler and S. Wartewig, Makromol. Chem., Macromol. Symp., 31, 123 (1990).
Core/shell latex particles are usually prepared by a series of consecutive emulsion polymerisation sequences with different monomer types, where the second (third, etc.) stage monomer is polymerised in the presence of “seed” latex particles. These seed latex particles may be prepared in a separate step, or formed in situ during the emulsion polymerisation. The resulting latexes are commonly referred to as “core/shell” latexes, implying a particle structure with the initially polymerised polymer located at the centre of the particle, and the later-formed polymer(s) becoming incorporated into the outer shell layer.
Such core/shell latexes are utilised in end-use applications such as architectural and automotive coatings, as impact modifiers in advanced engineering plastics to improve the impact strength and toughness, in adhesives to provide an optimum peel strength, and in many other high-value-added products in areas such as membrane separation and biotechnology.